Touch explorer does not cancel long press correctly causing system crash.

1. The touch explorer was not canceling long press runnable when a finger
   goes down. This was causing system crash in the scenario of one pointer
   down and not moving followed by another pointer down. Since the long press
   runnable posed when the first pointer went down was  not removed it was
   sending events with wrong pointer id leading to a crash.

bug:5271592

Change-Id: I40dd7dd21d465ecedd9413f00b3cedc6066fa22d